Bearing with a shape memory alloy component

ABSTRACT

The bearing assembly includes one or more elastomeric members loaded in a precompression by a shim that includes a shape memory alloy. The shape memory alloy is configured to generate the precompression in the elastomeric members upon a temperature change.

BACKGROUND

1. Technical Field:

The method and apparatus of the present application relates to abearing. The bearing can be used on a helicopter, for example.

2. Description of Related Art:

Certain bearings, such as elastomeric bearings, use alternating layersof metal shims and layers of elastomeric material. During fabrication ofthe bearing, considerable effort is made to install the layerselastomeric material so that each layer is in precompression. In somebearings, a lower grade of elastomeric material so that the elastomericportions can be squeezed into the bearing geometry.

Hence, there is a need for an improved bearing, and method ofmanufacturing the bearing.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the method and apparatusof the present application are set forth in the appended claims.However, the method and apparatus itself, as well as a preferred mode ofuse, and further objectives and advantages thereof, will best beunderstood by reference to the following detailed description when readin conjunction with the accompanying drawings, wherein:

FIG. 1 is a front view of a bearing assembly, according to anillustrative embodiment of the present application;

FIG. 2 is a cross-sectional view of a the bearing assembly, taken atsection lines 2-2 in FIG. 1, according to the illustrative embodiment ofthe present application; and

FIG. 3 is a schematic view of a method of manufacturing the bearingassembly, according to an illustrative embodiment of the presentapplication.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the apparatus and method are describedbelow. In the interest of clarity, all features of an actualimplementation may not be described in this specification. It will ofcourse be appreciated that in the development of any such actualembodiment, numerous implementation-specific decisions must be made toachieve the developer's specific goals, such as compliance withsystem-related and business-related constraints, which will vary fromone implementation to another. Moreover, it will be appreciated thatsuch a development effort might be complex and time-consuming but wouldnevertheless be a routine undertaking for those of ordinary skill in theart having the benefit of this disclosure.

In the specification, reference may be made to the spatial relationshipsbetween various components and to the spatial orientation of variousaspects of components as the devices are depicted in the attacheddrawings. However, as will be recognized by those skilled in the artafter a complete reading of the present application, the devices,members, apparatuses, etc. described herein may be positioned in anydesired orientation. Thus, the use of terms such as “above,” “below,”“upper,” “lower,” or other like terms to describe a spatial relationshipbetween various components or to describe the spatial orientation ofaspects of such components should be understood to describe a relativerelationship between the components or a spatial orientation of aspectsof such components, respectively, as the device described herein may beoriented in any desired direction.

The apparatus of the present application includes a bearing having oneor more elastomeric members in a precompression loading by a shim thatincludes a shape memory alloy. The shape memory alloy shim is configuredto generate the precompression upon a temperature change. The method ofthe present application includes manufacturing a bearing by utilizing ashape memory alloy shim to apply a precompression to the elastomericmembers.

Referring to FIGS. 1 and 2, an exemplary bearing assembly 101 isillustrated. Bearing assembly 101 can include a housing 103, a pluralityof shims 105 a-105 c, a plurality of elastomeric members 107 a-107 d,and an inner bearing member 109. Each shim 105 a-105 c includes a shapememory alloy that is configured to produce a compression preload forceupon the inwardly adjacent elastomeric member 107 b-107 d. For example,shim 105 a imparts compression in elastomeric member 107 b. Similarly,shim 105 b imparts compression in elastomeric member 107 c. Further,shim 105 c imparts compression in elastomeric member 107 d. Theprecompression force on the elastomeric members helps to extend its lifeby reducing indirect shear stress.

Each shim 105 a-105 c includes a shape memory alloy that causes theshims 105 a-105 c to constrict when subjected to an increase intemperature. Each shim 105 a-105 c is preferably in a cylindrical shape.However, bearing assembly 101 may include shims and elastomeric membersof other shapes as well. Further, it should be appreciated that bearingassembly 101 may include any number shims and elastomeric members.

Referring to FIG. 3, a method 301 of manufacturing bearing assembly 101is schematically illustrated. In a step 303, the elastomeric members 107a-107 d are preferably molded, but elastomeric members 107 a-107 d canbe manufactured in accordance with other methods as well. Further instep 303, housing 103 and inner bearing member 109 are fabricated.Housing 103 and inner bearing member 109 preferably include a rigidmetal material and may be manufactured in accordance with a variety ofmethods known in the art. Further in step 303, each shim 105 a-105 c isfabricated. Each shim 105 a-105 c preferably includes a shape memoryalloy that causes the size and shape of the part to return topredetermined original shape when subjected to heat. As such, each shim105 a-105 c is fabricated such that the ambient temperature size andshape is slightly smaller than the elastomeric member located inwardlyadjacent. A variety of shape memory alloys, which are known in the art,are acceptable in the composition of shims 105 a-105 c. For example, ashape memory alloy containing a nickel/titanium alloy can be used inshims 105 a-105 c.

Method 301 continues with a step 305 which includes subjecting shims 105a-105 c to a cold environment. A step 307 can include expanding eachshim 105 a-105 c with a mandrel. The combination of the cold environmentand expanding pressure from the mandrel causes the shims 105 a-105 c toexpand.

Method 301 continues with a step 309 of assembling shims 105 a-105 c,elastomeric members 107 a-107 d, along with inner bearing member 109.Adhesive can be used to secure each shim with an adjacent elastomericmember. For example, elastomeric member 107 d can be adhesively bondedto inner bearing member 109 and shim 105 c. Similarly, elastomericmember 107 c can be adhesively bonded to shim 105 c and shim 105 b.Further, elastomeric member 107 b can be adhesively bonded to shim 105 band shim 105 a.

Method 301 continues with a step 311 for allowing the shims to compressthe elastomeric members. As the parts are allowed to warm, shims 105a-105 c constrict due to the shape memory alloy material. As the shims105 a-105 c constrict, the elastomeric members 107 b-107 d compress.Once the shims 105 a-105 c have fully constricted, the remainingelastomeric member 107 a can be pressed and bonded into the gap betweenhousing 103 and shim 105 a. In some embodiments, heat can be applied tofacilitate the return of shims 105 a-105 c to their original shape, thusapplying a constricting force.

The method and apparatus of the present application provides significantadvantages, including: 1) providing a more cost efficient manufacturingtechnique for generating precompression in the elastomeric members; 2)providing a method of manufacturing that enables a higher grade ofelastomeric material to be used; and 3) providing more uniformprecompression across the elastomeric members.

The particular embodiments disclosed above are illustrative only, as themethod and apparatus may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Modifications, additions, or omissionsmay be made to the method and apparatus described herein withoutdeparting from the scope of the invention. The components of theapparatus may be integrated or separated. The steps of the method may beintegrated or separated. Moreover, the operations of the apparatus maybe performed by more, fewer, or other components.

Furthermore, no limitations are intended to the details of constructionor design herein shown, other than as described in the claims below. Itis therefore evident that the particular embodiments disclosed above maybe altered or modified and all such variations are considered within thescope and spirit of the application. Accordingly, the protection soughtherein is as set forth in the claims below.

To aid the Patent Office, and any readers of any patent issued on thisapplication in interpreting the claims appended hereto, applicants wishto note that they do not intend any of the appended claims to invokeparagraph 6 of 35 U.S.C. § 112 as it exists on the date of filing hereofunless the words “means for” or “step for” are explicitly used in theparticular claim.

1. A bearing assembly comprising: a housing; an inner bearing member; anelastomeric member; a shim that includes a shape memory alloy that isconfigured to apply a compressive force on the elastomeric member whensubjected to a temperature change.
 2. The bearing assembly according toclaim 1, further comprising: an adhesive layer between the shim and theelastomeric member.
 3. The bearing assembly according to claim 1,wherein the shim is approximately cylindrically shaped.
 4. The bearingassembly according to claim 1, wherein the inner bearing member isapproximately cylindrically shaped.
 5. The bearing assembly according toclaim 1, wherein the temperature changes is an increase in temperature.6. The bearing assembly according to claim 1, wherein the shape memoryalloy includes a nickel/titanium alloy.
 7. The bearing assemblyaccording to claim 1, further comprising: an additional elastomericmember located between the shim and an inner surface of the housing. 8.A bearing assembly comprising: a housing; an inner bearing member; aplurality of elastomeric members; a plurality of shims, each shimincluding a shape memory alloy.
 9. The bearing assembly according toclaim 8, wherein each shim is configured to constrict each elastomericmember when subjected to an increase in temperature.
 10. The bearingassembly according to claim 8, wherein each elastomeric member and eachshim member are approximately cylindrically shaped.
 11. The bearingassembly according to claim 8, further comprising: an adhesive layerbetween each shim and elastomeric member.
 12. A method of manufacturinga bearing assembly, the method comprising the steps of: providing aninner member, a housing, a shim, and an elastomeric member; cooling theshim; assembling the inner member, the housing, the shim and theelastomeric member; and heating the shim, thereby causing the shim tocompress the elastomeric member.
 13. The method according to claim 12,further comprising the step of: applying an adhesive between the shimand the elastomeric member.
 14. The method according to claim 12,further comprising the step of: expanding the shim with a mandrel inconjunction with the step of cooling the shim.
 15. The method accordingto claim 12, wherein the shim is comprised of a shape memory alloy. 16.The method according to claim 15, wherein the shape memory alloy is anickel/titanium alloy.
 17. The method according to claim 12, wherein theshim is approximately cylindrical.
 18. The method according to claim 12,wherein the step of providing the shim and the elastomeric memberincludes providing the elastomeric member at a larger size and shapethan the shim.